diff --git a/openraft/src/raft/message/append_entries.rs b/openraft/src/raft/message/append_entries.rs
new file mode 100644
index 000000000..5980110d8
--- /dev/null
+++ b/openraft/src/raft/message/append_entries.rs
@@ -0,0 +1,117 @@
+use std::fmt;
+
+use crate::display_ext::DisplayOptionExt;
+use crate::display_ext::DisplaySlice;
+use crate::LogId;
+use crate::MessageSummary;
+use crate::NodeId;
+use crate::RaftTypeConfig;
+use crate::Vote;
+
+/// An RPC sent by a cluster leader to replicate log entries (§5.3), and as a heartbeat (§5.2).
+#[derive(Clone)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize), serde(bound = ""))]
+pub struct AppendEntriesRequest<C: RaftTypeConfig> {
+    pub vote: Vote<C::NodeId>,
+
+    pub prev_log_id: Option<LogId<C::NodeId>>,
+
+    /// The new log entries to store.
+    ///
+    /// This may be empty when the leader is sending heartbeats. Entries
+    /// are batched for efficiency.
+    pub entries: Vec<C::Entry>,
+
+    /// The leader's committed log id.
+    pub leader_commit: Option<LogId<C::NodeId>>,
+}
+
+impl<C: RaftTypeConfig> fmt::Debug for AppendEntriesRequest<C>
+where C::D: fmt::Debug
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("AppendEntriesRequest")
+            .field("vote", &self.vote)
+            .field("prev_log_id", &self.prev_log_id)
+            .field("entries", &self.entries)
+            .field("leader_commit", &self.leader_commit)
+            .finish()
+    }
+}
+
+impl<C: RaftTypeConfig> MessageSummary<AppendEntriesRequest<C>> for AppendEntriesRequest<C> {
+    fn summary(&self) -> String {
+        format!(
+            "vote={}, prev_log_id={}, leader_commit={}, entries={}",
+            self.vote,
+            self.prev_log_id.summary(),
+            self.leader_commit.summary(),
+            DisplaySlice::<_>(self.entries.as_slice())
+        )
+    }
+}
+
+/// The response to an `AppendEntriesRequest`.
+///
+/// [`RaftNetwork::send_append_entries`] returns this type only when received an RPC reply.
+/// Otherwise it should return [`RPCError`].
+///
+/// [`RPCError`]: crate::error::RPCError
+/// [`RaftNetwork::send_append_entries`]: crate::network::RaftNetwork::send_append_entries
+#[derive(Debug)]
+#[derive(PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize), serde(bound = ""))]
+pub enum AppendEntriesResponse<NID: NodeId> {
+    /// Successfully replicated all log entries to the target node.
+    Success,
+
+    /// Successfully sent the first portion of log entries.
+    ///
+    /// [`RaftNetwork::send_append_entries`] can return a partial success.
+    /// For example, it tries to send log entries `[1-2..3-10]`, the application is allowed to send
+    /// just `[1-2..1-3]` and return `PartialSuccess(1-3)`,
+    ///
+    /// ### Caution
+    ///
+    /// The returned matching log id must be **greater than or equal to** the first log
+    /// id([`AppendEntriesRequest::prev_log_id`]) of the entries to send. If no RPC reply is
+    /// received, [`RaftNetwork::send_append_entries`] must return an [`RPCError`] to inform
+    /// Openraft that the first log id([`AppendEntriesRequest::prev_log_id`]) may not match on
+    /// the remote target node.
+    ///
+    /// [`RPCError`]: crate::error::RPCError
+    /// [`RaftNetwork::send_append_entries`]: crate::network::RaftNetwork::send_append_entries
+    PartialSuccess(Option<LogId<NID>>),
+
+    /// The first log id([`AppendEntriesRequest::prev_log_id`]) of the entries to send does not
+    /// match on the remote target node.
+    Conflict,
+
+    /// Seen a vote `v` that does not hold `mine_vote >= v`.
+    /// And a leader's vote(committed vote) must be total order with other vote.
+    /// Therefore it has to be a higher vote: `mine_vote < v`
+    HigherVote(Vote<NID>),
+}
+
+impl<NID: NodeId> AppendEntriesResponse<NID> {
+    pub fn is_success(&self) -> bool {
+        matches!(*self, AppendEntriesResponse::Success)
+    }
+
+    pub fn is_conflict(&self) -> bool {
+        matches!(*self, AppendEntriesResponse::Conflict)
+    }
+}
+
+impl<NID: NodeId> fmt::Display for AppendEntriesResponse<NID> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            AppendEntriesResponse::Success => write!(f, "Success"),
+            AppendEntriesResponse::PartialSuccess(m) => {
+                write!(f, "PartialSuccess({})", m.display())
+            }
+            AppendEntriesResponse::HigherVote(vote) => write!(f, "Higher vote, {}", vote),
+            AppendEntriesResponse::Conflict => write!(f, "Conflict"),
+        }
+    }
+}
diff --git a/openraft/src/raft/message/client_write.rs b/openraft/src/raft/message/client_write.rs
new file mode 100644
index 000000000..b063c8c89
--- /dev/null
+++ b/openraft/src/raft/message/client_write.rs
@@ -0,0 +1,42 @@
+use std::fmt::Debug;
+
+use crate::AppDataResponse;
+use crate::LogId;
+use crate::Membership;
+use crate::MessageSummary;
+use crate::RaftTypeConfig;
+
+/// The response to a client-request.
+#[cfg_attr(
+    feature = "serde",
+    derive(serde::Deserialize, serde::Serialize),
+    serde(bound = "C::R: AppDataResponse")
+)]
+pub struct ClientWriteResponse<C: RaftTypeConfig> {
+    /// The id of the log that is applied.
+    pub log_id: LogId<C::NodeId>,
+
+    /// Application specific response data.
+    pub data: C::R,
+
+    /// If the log entry is a change-membership entry.
+    pub membership: Option<Membership<C::NodeId, C::Node>>,
+}
+
+impl<C: RaftTypeConfig> Debug for ClientWriteResponse<C>
+where C::R: Debug
+{
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("ClientWriteResponse")
+            .field("log_id", &self.log_id)
+            .field("data", &self.data)
+            .field("membership", &self.membership)
+            .finish()
+    }
+}
+
+impl<C: RaftTypeConfig> MessageSummary<ClientWriteResponse<C>> for ClientWriteResponse<C> {
+    fn summary(&self) -> String {
+        format!("log_id: {}, membership: {:?}", self.log_id, self.membership)
+    }
+}
diff --git a/openraft/src/raft/message/install_snapshot.rs b/openraft/src/raft/message/install_snapshot.rs
new file mode 100644
index 000000000..3372e3f81
--- /dev/null
+++ b/openraft/src/raft/message/install_snapshot.rs
@@ -0,0 +1,47 @@
+use crate::MessageSummary;
+use crate::NodeId;
+use crate::RaftTypeConfig;
+use crate::SnapshotMeta;
+use crate::Vote;
+
+/// An RPC sent by the Raft leader to send chunks of a snapshot to a follower (§7).
+#[derive(Clone, Debug)]
+#[derive(PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize), serde(bound = ""))]
+pub struct InstallSnapshotRequest<C: RaftTypeConfig> {
+    pub vote: Vote<C::NodeId>,
+
+    /// Metadata of a snapshot: snapshot_id, last_log_ed membership etc.
+    pub meta: SnapshotMeta<C::NodeId, C::Node>,
+
+    /// The byte offset where this chunk of data is positioned in the snapshot file.
+    pub offset: u64,
+    /// The raw bytes of the snapshot chunk, starting at `offset`.
+    pub data: Vec<u8>,
+
+    /// Will be `true` if this is the last chunk in the snapshot.
+    pub done: bool,
+}
+
+impl<C: RaftTypeConfig> MessageSummary<InstallSnapshotRequest<C>> for InstallSnapshotRequest<C> {
+    fn summary(&self) -> String {
+        format!(
+            "vote={}, meta={}, offset={}, len={}, done={}",
+            self.vote,
+            self.meta,
+            self.offset,
+            self.data.len(),
+            self.done
+        )
+    }
+}
+
+/// The response to an `InstallSnapshotRequest`.
+#[derive(Debug)]
+#[derive(PartialEq, Eq)]
+#[derive(derive_more::Display)]
+#[display(fmt = "{{vote:{}}}", vote)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize), serde(bound = ""))]
+pub struct InstallSnapshotResponse<NID: NodeId> {
+    pub vote: Vote<NID>,
+}
diff --git a/openraft/src/raft/message/mod.rs b/openraft/src/raft/message/mod.rs
new file mode 100644
index 000000000..786fca895
--- /dev/null
+++ b/openraft/src/raft/message/mod.rs
@@ -0,0 +1,18 @@
+//! Raft protocol messages and types.
+//!
+//! Request and response types for an application to talk to the Raft,
+//! and are also used by network layer to talk to other Raft nodes.
+
+mod append_entries;
+mod install_snapshot;
+mod vote;
+
+mod client_write;
+
+pub use append_entries::AppendEntriesRequest;
+pub use append_entries::AppendEntriesResponse;
+pub use client_write::ClientWriteResponse;
+pub use install_snapshot::InstallSnapshotRequest;
+pub use install_snapshot::InstallSnapshotResponse;
+pub use vote::VoteRequest;
+pub use vote::VoteResponse;
diff --git a/openraft/src/raft/message/vote.rs b/openraft/src/raft/message/vote.rs
new file mode 100644
index 000000000..7c7336145
--- /dev/null
+++ b/openraft/src/raft/message/vote.rs
@@ -0,0 +1,59 @@
+use std::fmt;
+
+use crate::display_ext::DisplayOptionExt;
+use crate::LogId;
+use crate::MessageSummary;
+use crate::NodeId;
+use crate::Vote;
+
+/// An RPC sent by candidates to gather votes (§5.2).
+#[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize), serde(bound = ""))]
+pub struct VoteRequest<NID: NodeId> {
+    pub vote: Vote<NID>,
+    pub last_log_id: Option<LogId<NID>>,
+}
+
+impl<NID: NodeId> fmt::Display for VoteRequest<NID> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{{vote:{}, last_log:{}}}", self.vote, self.last_log_id.display(),)
+    }
+}
+
+impl<NID: NodeId> MessageSummary<VoteRequest<NID>> for VoteRequest<NID> {
+    fn summary(&self) -> String {
+        self.to_string()
+    }
+}
+
+impl<NID: NodeId> VoteRequest<NID> {
+    pub fn new(vote: Vote<NID>, last_log_id: Option<LogId<NID>>) -> Self {
+        Self { vote, last_log_id }
+    }
+}
+
+/// The response to a `VoteRequest`.
+#[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize), serde(bound = ""))]
+pub struct VoteResponse<NID: NodeId> {
+    /// vote after a node handling vote-request.
+    /// Thus `resp.vote >= req.vote` always holds.
+    pub vote: Vote<NID>,
+
+    /// Will be true if the candidate received a vote from the responder.
+    pub vote_granted: bool,
+
+    /// The last log id stored on the remote voter.
+    pub last_log_id: Option<LogId<NID>>,
+}
+
+impl<NID: NodeId> MessageSummary<VoteResponse<NID>> for VoteResponse<NID> {
+    fn summary(&self) -> String {
+        format!(
+            "{{granted:{}, {}, last_log:{:?}}}",
+            self.vote_granted,
+            self.vote,
+            self.last_log_id.map(|x| x.to_string())
+        )
+    }
+}
diff --git a/openraft/src/raft/mod.rs b/openraft/src/raft/mod.rs
index f391f54b8..59861d4fd 100644
--- a/openraft/src/raft/mod.rs
+++ b/openraft/src/raft/mod.rs
@@ -1,5 +1,6 @@
 //! Public Raft interface and data types.
 
+mod message;
 mod raft_inner;
 
 use std::collections::BTreeMap;
@@ -11,6 +12,13 @@ use std::sync::Arc;
 use std::time::Duration;
 
 use maplit::btreemap;
+pub use message::AppendEntriesRequest;
+pub use message::AppendEntriesResponse;
+pub use message::ClientWriteResponse;
+pub use message::InstallSnapshotRequest;
+pub use message::InstallSnapshotResponse;
+pub use message::VoteRequest;
+pub use message::VoteResponse;
 use tokio::io::AsyncRead;
 use tokio::io::AsyncSeek;
 use tokio::io::AsyncWrite;
@@ -29,8 +37,6 @@ use crate::core::replication_lag;
 use crate::core::sm;
 use crate::core::RaftCore;
 use crate::core::Tick;
-use crate::display_ext::DisplayOptionExt;
-use crate::display_ext::DisplaySlice;
 use crate::engine::Engine;
 use crate::engine::EngineConfig;
 use crate::entry::FromAppData;
@@ -56,14 +62,11 @@ use crate::AsyncRuntime;
 use crate::ChangeMembers;
 use crate::LogId;
 use crate::LogIdOptionExt;
-use crate::Membership;
 use crate::MessageSummary;
 use crate::NodeId;
 use crate::OptionalSend;
 use crate::RaftState;
-use crate::SnapshotMeta;
 use crate::StorageHelper;
-use crate::Vote;
 
 /// Configuration of types used by the [`Raft`] core engine.
 ///
@@ -967,240 +970,3 @@ impl fmt::Display for ExternalCommand {
         }
     }
 }
-
-/// An RPC sent by a cluster leader to replicate log entries (§5.3), and as a heartbeat (§5.2).
-#[derive(Clone)]
-#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize), serde(bound = ""))]
-pub struct AppendEntriesRequest<C: RaftTypeConfig> {
-    pub vote: Vote<C::NodeId>,
-
-    pub prev_log_id: Option<LogId<C::NodeId>>,
-
-    /// The new log entries to store.
-    ///
-    /// This may be empty when the leader is sending heartbeats. Entries
-    /// are batched for efficiency.
-    pub entries: Vec<C::Entry>,
-
-    /// The leader's committed log id.
-    pub leader_commit: Option<LogId<C::NodeId>>,
-}
-
-impl<C: RaftTypeConfig> Debug for AppendEntriesRequest<C>
-where C::D: Debug
-{
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("AppendEntriesRequest")
-            .field("vote", &self.vote)
-            .field("prev_log_id", &self.prev_log_id)
-            .field("entries", &self.entries)
-            .field("leader_commit", &self.leader_commit)
-            .finish()
-    }
-}
-
-impl<C: RaftTypeConfig> MessageSummary<AppendEntriesRequest<C>> for AppendEntriesRequest<C> {
-    fn summary(&self) -> String {
-        format!(
-            "vote={}, prev_log_id={}, leader_commit={}, entries={}",
-            self.vote,
-            self.prev_log_id.summary(),
-            self.leader_commit.summary(),
-            DisplaySlice::<_>(self.entries.as_slice())
-        )
-    }
-}
-
-/// The response to an `AppendEntriesRequest`.
-///
-/// [`RaftNetwork::send_append_entries`] returns this type only when received an RPC reply.
-/// Otherwise it should return [`RPCError`].
-///
-/// [`RPCError`]: crate::error::RPCError
-/// [`RaftNetwork::send_append_entries`]: crate::network::RaftNetwork::send_append_entries
-#[derive(Debug)]
-#[derive(PartialEq, Eq)]
-#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize), serde(bound = ""))]
-pub enum AppendEntriesResponse<NID: NodeId> {
-    /// Successfully replicated all log entries to the target node.
-    Success,
-
-    /// Successfully sent the first portion of log entries.
-    ///
-    /// [`RaftNetwork::send_append_entries`] can return a partial success.
-    /// For example, it tries to send log entries `[1-2..3-10]`, the application is allowed to send
-    /// just `[1-2..1-3]` and return `PartialSuccess(1-3)`,
-    ///
-    /// ### Caution
-    ///
-    /// The returned matching log id must be **greater than or equal to** the first log
-    /// id([`AppendEntriesRequest::prev_log_id`]) of the entries to send. If no RPC reply is
-    /// received, [`RaftNetwork::send_append_entries`] must return an [`RPCError`] to inform
-    /// Openraft that the first log id([`AppendEntriesRequest::prev_log_id`]) may not match on
-    /// the remote target node.
-    ///
-    /// [`RPCError`]: crate::error::RPCError
-    /// [`RaftNetwork::send_append_entries`]: crate::network::RaftNetwork::send_append_entries
-    PartialSuccess(Option<LogId<NID>>),
-
-    /// The first log id([`AppendEntriesRequest::prev_log_id`]) of the entries to send does not
-    /// match on the remote target node.
-    Conflict,
-
-    /// Seen a vote `v` that does not hold `mine_vote >= v`.
-    /// And a leader's vote(committed vote) must be total order with other vote.
-    /// Therefore it has to be a higher vote: `mine_vote < v`
-    HigherVote(Vote<NID>),
-}
-
-impl<NID: NodeId> AppendEntriesResponse<NID> {
-    pub fn is_success(&self) -> bool {
-        matches!(*self, AppendEntriesResponse::Success)
-    }
-
-    pub fn is_conflict(&self) -> bool {
-        matches!(*self, AppendEntriesResponse::Conflict)
-    }
-}
-
-impl<NID: NodeId> fmt::Display for AppendEntriesResponse<NID> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match self {
-            AppendEntriesResponse::Success => write!(f, "Success"),
-            AppendEntriesResponse::PartialSuccess(m) => {
-                write!(f, "PartialSuccess({})", m.display())
-            }
-            AppendEntriesResponse::HigherVote(vote) => write!(f, "Higher vote, {}", vote),
-            AppendEntriesResponse::Conflict => write!(f, "Conflict"),
-        }
-    }
-}
-
-/// An RPC sent by candidates to gather votes (§5.2).
-#[derive(Debug, Clone, PartialEq, Eq)]
-#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize), serde(bound = ""))]
-pub struct VoteRequest<NID: NodeId> {
-    pub vote: Vote<NID>,
-    pub last_log_id: Option<LogId<NID>>,
-}
-
-impl<NID: NodeId> fmt::Display for VoteRequest<NID> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "{{vote:{}, last_log:{}}}", self.vote, self.last_log_id.display(),)
-    }
-}
-
-impl<NID: NodeId> MessageSummary<VoteRequest<NID>> for VoteRequest<NID> {
-    fn summary(&self) -> String {
-        self.to_string()
-    }
-}
-
-impl<NID: NodeId> VoteRequest<NID> {
-    pub fn new(vote: Vote<NID>, last_log_id: Option<LogId<NID>>) -> Self {
-        Self { vote, last_log_id }
-    }
-}
-
-/// The response to a `VoteRequest`.
-#[derive(Debug, Clone, PartialEq, Eq)]
-#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize), serde(bound = ""))]
-pub struct VoteResponse<NID: NodeId> {
-    /// vote after a node handling vote-request.
-    /// Thus `resp.vote >= req.vote` always holds.
-    pub vote: Vote<NID>,
-
-    /// Will be true if the candidate received a vote from the responder.
-    pub vote_granted: bool,
-
-    /// The last log id stored on the remote voter.
-    pub last_log_id: Option<LogId<NID>>,
-}
-
-impl<NID: NodeId> MessageSummary<VoteResponse<NID>> for VoteResponse<NID> {
-    fn summary(&self) -> String {
-        format!(
-            "{{granted:{}, {}, last_log:{:?}}}",
-            self.vote_granted,
-            self.vote,
-            self.last_log_id.map(|x| x.to_string())
-        )
-    }
-}
-
-/// An RPC sent by the Raft leader to send chunks of a snapshot to a follower (§7).
-#[derive(Clone, Debug)]
-#[derive(PartialEq, Eq)]
-#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize), serde(bound = ""))]
-pub struct InstallSnapshotRequest<C: RaftTypeConfig> {
-    pub vote: Vote<C::NodeId>,
-
-    /// Metadata of a snapshot: snapshot_id, last_log_ed membership etc.
-    pub meta: SnapshotMeta<C::NodeId, C::Node>,
-
-    /// The byte offset where this chunk of data is positioned in the snapshot file.
-    pub offset: u64,
-    /// The raw bytes of the snapshot chunk, starting at `offset`.
-    pub data: Vec<u8>,
-
-    /// Will be `true` if this is the last chunk in the snapshot.
-    pub done: bool,
-}
-
-impl<C: RaftTypeConfig> MessageSummary<InstallSnapshotRequest<C>> for InstallSnapshotRequest<C> {
-    fn summary(&self) -> String {
-        format!(
-            "vote={}, meta={}, offset={}, len={}, done={}",
-            self.vote,
-            self.meta,
-            self.offset,
-            self.data.len(),
-            self.done
-        )
-    }
-}
-
-/// The response to an `InstallSnapshotRequest`.
-#[derive(Debug)]
-#[derive(PartialEq, Eq)]
-#[derive(derive_more::Display)]
-#[display(fmt = "{{vote:{}}}", vote)]
-#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize), serde(bound = ""))]
-pub struct InstallSnapshotResponse<NID: NodeId> {
-    pub vote: Vote<NID>,
-}
-
-/// The response to a client-request.
-#[cfg_attr(
-    feature = "serde",
-    derive(serde::Deserialize, serde::Serialize),
-    serde(bound = "C::R: AppDataResponse")
-)]
-pub struct ClientWriteResponse<C: RaftTypeConfig> {
-    /// The id of the log that is applied.
-    pub log_id: LogId<C::NodeId>,
-
-    /// Application specific response data.
-    pub data: C::R,
-
-    /// If the log entry is a change-membership entry.
-    pub membership: Option<Membership<C::NodeId, C::Node>>,
-}
-
-impl<C: RaftTypeConfig> Debug for ClientWriteResponse<C>
-where C::R: Debug
-{
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        f.debug_struct("ClientWriteResponse")
-            .field("log_id", &self.log_id)
-            .field("data", &self.data)
-            .field("membership", &self.membership)
-            .finish()
-    }
-}
-
-impl<C: RaftTypeConfig> MessageSummary<ClientWriteResponse<C>> for ClientWriteResponse<C> {
-    fn summary(&self) -> String {
-        format!("log_id: {}, membership: {:?}", self.log_id, self.membership)
-    }
-}